Asynchronous motor drive operability field with two-link structure of frequency converter

Abstract

The article presents an approach to determining the electric drive’s operability based on an asynchronous motor with a short-circuited rotor and a two-link frequency converter. Mathematical description of the frequency-controlled electric drive is performed, in particular, selection of criteria taking into account an electric and mechanical part. The harmonic current distortion coefficient as a component of the power coefficient is used for the determination of the energy criterion. The mechanical criterion is the coefficient of the electromagnetic moment pulsation, on the value of which the conjugated equipment depends. The operability field is represented as a function of three variables: (a) rotor speed, (b) current harmonic distortion coefficient, and (c) electromagnetic moment pulsation coefficient. The obtained surface makes it possible to determine the actual state of the electric drive and to estimate the reserve of operability, which allows reducing the operating costs in terms of repair and maintenance.

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“…-odd integer; p-number of pole pairs; r s -number of rotor rods. The stator current I st , taking into account the AM defects at a sinusoidal voltage, will be formed according to (5), and when powered from an autonomous inverter, according to (6).…”

“…where M (n) , M (qp) , M (di) -components of the electromagnetic moment (N m ), created as a result of the interaction of the n harmonics for the stator current and the rotor flux linkage, d i harmonics for the stator current and the rotor flux linkage, q harmonic for the stator current and p harmonic of the rotor flux linkage; I st(n) , I st(q) , I st(di) , ψ r(n) , ψ r(p) , ψ r(di) -harmonic components of stator current and rotor flux linkage (A, Wb); θ (qp) -angle between the q harmonic of the stator current and the p harmonic of the rotor flux linkage, θ (di) -angle between the d i harmonics of the stator current and the rotor flux linkage (rad) (6).…”